<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>
	<body>
		<script>
			function dateGirl(flag,fn){
				if(flag==1){
//					没穿fn值,fn为undefined，布尔值为false
					if(fn){
						fn();
					}
					fn && fn();
				}
			}
			
			function movie(){
				console.log('去看电影啦');
			}
			
			dateGirl(1,movie);
			
			
			
			
			
			
			
			
			
			
			
			
			
			
			
			
			
			
			
			
			
			
			
		</script>
	</body>
</html>
